ELECTROCHEMICAL FLUORINATION OF AROMATIC-COMPOUNDS IN LIQUID R(4)NF-CENTER-DOT-MHF .4. FLUORINATION OF CHLOROBENZENE

Electrochemical fluorination of chlorobenzene (1) in neat Et(4)NF . mHF (Et = C2H5: m = 4.0, 4.45 and 4.7) was carried out on a platinum anode at 2.3 or 2.5 V vs. Ag/Ag+ (0.01 M; M = mol dm(-3)). As the primary products, 1-chloro-2-fluorobenzene (2) and 1-chloro-4-fluorobenzene (3) were obtained, whose molar ratio (2/3) was about 1:3. The product 2 was further fluorinated to 1-chloro-3,6,6-trifluoro-1,4-cyclohexadiene (2a) with a high yield. On the other hand, the electrochemical fluorination of 3 yielded 3-chloro-3,6,6-trifluoro-1,4-cyclohexadiene (3a), 2-chloro-5,5,6-trifluoro-1,3-cyclohexadiene (3b) and 3,3,6, 6-tetrafluoro-1,4-cyclohexadiene (6a). A larger amount of 6a was obtained at the final stages of the electrolyses of 1 and 3. The yield of 6a varied with the electrolysis conditions.